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A possible role for epigenetic feedback regulation in the dynamics of the epithelial-mesenchymal transition (EMT)
No full textThe epithelial-mesenchymal transition (EMT) often plays a critical role in cancer metastasis and chemoresistance, and decoding its dynamics is crucial to design effective therapeutics. EMT is regulated at multiple levels-transcriptional, translational, protein stability and epigenetics; the mechanisms by which epigenetic regulation can alter the dynamics of EMT remain elusive. Here, to identify the possible effects of epigenetic regulation in EMT, we incorporate a feedback term in our previously proposed model of EMT regulation of the miR-200/ZEB/miR-34/SNAIL circuit. This epigenetic feedback that stabilizes long-term transcriptional activity can alter the relative stability and distribution of states in a given cell population, particularly when incorporated in the inhibitory effect on miR-200 from ZEB. This feedback can stabilize the mesenchymal state, thus making transitions out of that state difficult. Conversely, epigenetic regulation of the self-activation of ZEB has only minor effects. Our model predicts that this effect could be seen in experiments, when epithelial cells are treated with an external EMT-inducing signal for a sufficiently long period of time and then allowed to recover. Our preliminary experimental data indicates that a chronic TGF-beta exposure gives rise to irreveversible EMT state; i.e. unable to reverse back to the epithelial state. Thus, this integrated theoretical-experimental approach yields insights into how an epigenetic feedback may alter the dynamics of EMT
Modeling and analysis of solar thermal and biomass hybrid power plants
No full textStand-alone renewable energy plants are usually unable to generate stable electrical power because of resource intermittency. Consequently, grid operators find it difficult to plan power supply. Employing electrical storage, thermal energy storage, and hybridization in stand-alone plants could provide some solutions. However, electrical and thermal storage have limitations at megawatt scales with major ones being not cost-effective and the increased solar field. Hybridization of multiple sources of renewable energy is a promising way to address intermittency issues. This paper presents thermodynamic modeling for sizing a steam Rankine cycle based solar-biomass hybrid power plant. Solar system uses parabolic trough technology, and biomass system uses fluidized bed combustion technology to generate steam for power generation. The biomass system plays a significant role in the hybrid operation during the solar intermittency periods. Also, the boiler in a stand-alone mode can generate power post sunshine hours to meet the power demand. Further, the paper presents a rase study to emphasize parameters such as solar field area requirements, biomass requirements, system efficiency, intermittency aspects, capacity utilization factor, capex, and levelized cost of electricity for various scales of hybrid systems. The results suggest that hybridization could be a possible sustainable solution
A new Neuro-Fuzzy Inference System with Dynamic Neurons (NFIS-DN) for system identification and time series forecasting
No full textA new Neuro-Fuzzy Inference System with Dynamic Neurons or NFIS-DN is presented here for discrete time dynamic system identification and time series forecasting problems. The proposed dynamic system based neuron, referred to as Dynamic Neuron (DN) is realized by a discrete-time nonlinear state-space model. The DN is designed such way, that the output considers only the effect of finite past instances, enabling the system with finite memory. The NFIS-DN model has five layers, and DNs are employed only in the layers handling crisp values. The antecedent and the consequent parameters of NFIS-DN are updated using a self-regulated backpropagation through time learning algorithm. The performance evaluation of NFIS-DN has been carried-out using benchmark problems in the areas of nonlinear system identification and time series forecasting. The results are compared with the state-of-the-art method on the neural fuzzy networks. The obtained results clearly suggest that the NFIS-DN performs significantly better while using a smaller or similar number of fuzzy rules. Finally the practical application of the NFIS-DN has been demonstrated using two real-world problems
Mechanical characterization of the Poly lactic acid (PLA) composites prepared through the Fused Deposition Modelling process
No full textThis research article focuses on developing biodegradable polymer composites for general - purpose engineering applications that can efficiently replace the existing polymeric materials and certain metals by their enhanced material properties such as tensile strength, biodegradability, hardness and other properties. Recent studies have placed Poly lactic acid (PLA) in a prime position for production of common commercial and engineering products due to its commendable mechanical properties coupled with biodegradability. Therefore, in this study, attempts are made to assess the influence of carbon fibers and nylon glass fibers on the overall mechanical properties of additive manufactured PLA composites prepared by Fused Deposition Modelling (FDM). In addition to this, special attention has been paid to study the mechanical characteristics of the polymer blend of Glycol modified Polyethylene teraphthalate (PETG) with PLA prepared using the same method. The mechanical properties for the materials were evaluated using the tensile test, Rockwell hardness test, scanning electron microscopy (SEM) and Fourier Transform Infrared (FTIR) spectroscopy. The experimental results reveal that in contrast to other polymers, the polymer blend of PLA + PETG would be an ideal choice due to its superior mechanical properties that can prove useful in various engineering applications. Therefore, the materials studied here can be used in the production of regular biodegradable commercial products like pens, cases, food containers, bottles, electronic packaging and other related products which when otherwise disposed can cause widespread discomfort to the delicate balance in the environment by polluting various aspects of nature. Thus, jeopardizing the health of various fauna and flora present in nature
Boosted top quark polarization
No full textIn top quark production, the polarization of top quarks, decided by the chiral structure of couplings, is likely to be modified in the presence of any new physics contribution to the production. Hence, it is a good discriminator for those new physics models wherein the couplings have a chiral structure different than that in the Standard Model. In this paper, we construct probes of the polarization of a top quark decaying hadronically, using easily accessible kinematic variables such as the energy fraction or angular correlations of the decay products. Tagging the boosted top quark using the jet substructure technique, we study the robustness of these observables for a benchmark process, W' -> tb. We demonstrate that the energy fraction of b jet in the laboratory frame and a new angular variable, constructed by us in the top rest frame, are both very powerful tools to discriminate between the left and right polarized top quarks. Based on the polarization-sensitive angular variables, we construct asymmetries that reflect the polarization. We study the efficacy of these variables for two new physics processes that give rise to boosted top quarks: (i) the decay of the top squark in the context of supersymmetry searches and (ii) decays of the Kaluza-Klein (KK) graviton and KK gluon, in the Randall-Sundrum model. Remarkably, it is found that the asymmetry can vary over a wide range about +20% to -20%. The dependence of asymmetry on top quark couplings of the new particles present in these models beyond the SM is also investigated in detail
Stereoselective addition of Grignard reagents to sulfinimines derived from tartrate diol (threitol): Generation of chiral building blocks for the collective total synthesis of lentiginosine, conhydrine and methyldihydropalustramate
No full textA systematic investigation of the addition of Grignard reagents to sulfinimines derived from tartaric acid diol was undertaken. It was observed that the chirality of the inherent tartrate moiety influences the diastereoselectivity of the resultant sulfinamides formed in the reaction. The formed products serve as excellent building blocks for the synthesis of natural products. This has been demonstrated in the collective total synthesis of lentiginosine, (+)-alpha-conhydrine and methyldihydropalustramate
A review of the major drivers of the terrestrial carbon uptake: model-based assessments, consensus, and uncertainties
No full textTerrestrial and oceanic carbon sinks together sequester >50% of the anthropogenic emissions, and the major uncertainty in the global carbon budget is related to the terrestrial carbon cycle. Hence, it is important to understand the major drivers of the land carbon uptake to make informed decisions on climate change mitigation policies. In this paper, we assess the major drivers of the land carbon uptake-CO2 fertilization, nitrogen deposition, climate change, and land use/land cover changes (LULCC)-from existing literature for the historical period and future scenarios, focusing on the results from fifth Coupled Models Intercomparison Project (CMIP5). The existing literature shows that the LULCC fluxes have led to a decline in the terrestrial carbon stocks during the historical period, despite positive contributions from CO2 fertilization and nitrogen deposition. However, several studies find increases in the land carbon sink in recent decades and suggest that CO2 fertilization is the primary driver (up to 85%) of this increase followed by nitrogen deposition (similar to 10%-20%). For the 21st century, terrestrial carbon stocks are projected to increase in the majority of CMIP5 simulations under the representative concentration pathway 2.6 (RCP2.6), RCP4.5, and RCP8.5 scenarios, mainly due to CO2 fertilization. These projections indicate that the effects of nitrogen deposition in future scenarios are small (similar to 2%-10%), and climate warming would lead to a loss of land carbon. The vast majority of the studies consider the effects of only one or two of the drivers, impairing comprehensive assessments of the relative contributions of the drivers. Further, the broad range in magnitudes and scenario/model dependence of the sensitivity factors pose challenges in unambiguous projections of land carbon uptake. Improved representation of processes such as LULCC, fires, nutrient limitation and permafrost thawing in the models are necessary to constrain the present-day carbon cycle and for more accurate future projections
Performance Comparison of Multi-objective Algorithms for Test Case Prioritization During Web Application Testing
No full textTest case prioritization (TCP) is a widely accepted and extensively used strategy during regression testing. TCP is the permutation of test cases to enhance efficiency in achieving performance goals. These goals can belong to the category of single objective problem or multi-objective problem. This empirical study focuses on three objectives wherein two objectives are to be maximized and the remaining one minimized. During this study, three websites and various versions were created on which non-dominated sorting genetic algorithm-II and variant of non-dominated sorting artificial bee colony algorithm were applied to prioritize sequence of test cases. The problem size varies from small-size fault matrix (34x27) to mid-size fault matrix (157x128). Performance of the two algorithms was measured on various parameters and also verified on the basis of statistical testing. An alternate approach for solving this multi-objective problem, based on dynamic programming, is also proposed in this study, and it is concluded that performance of this algorithm is at par with other suggested ones
Manipulation of Heteroatom Substitution on Nitrogen and Phosphorus Co-Doped Graphene as a High Active Catalyst for Hydrogen Evolution Reaction
No full textGraphene doped with heteroatoms is known to create a unique electronic structure with comparatively much higher active sites by the synergistic coupling effect. However, in the earlier attempts, the atomic structure of such co-doped graphene could not be altered; thus, there is a lack of reports discussing the influence of the atomic arrangement in the catalytic performance of the co-doped graphene. Here, by co-doping P and N atoms in graphene as a model system, we present a facile and two-step process wherein the sequence of doping helps in manipulating the heteroatom substitution, which is of great importance in defining better crystallinity and conductivity and favorable elemental functionalities and hence improving catalytic performance. The present method provides a clean, flexible, binder-free, and readily available electrocatalyst that avoids tedious conventional synthesis and device fabrication steps. The highest P-doping percentage (6 at. %) in the present work is superior to previous reports (3 at. %). By altering the sequence of N- and P-doping, the co-doped graphene electrode displayed excellent performance, with an increment of 148% in the sp(2) domain size and enormous lowering in overpotential and Tafel slope (78%). Further, the efficiency of the hydrogen evolution reaction catalyst sustains >98% for 20 h, which is significantly higher than the well-known MoSx (63%). Although here the P-N co-doped system was utilized as a proof of concept, this method could be adapted for other versatile co-doped graphene. This work may pave the way for the development of co-doped graphene-based devices where manipulation of atomic arrangement can result in a structure with properties desirable for catalytic or electronics applications
Remarkably selective biocompatible turn-on fluorescent probe for detection of Fe3+ in human blood samples and cells
No full textThe robust nature of a biocompatible fluorescent probe is demonstrated, by its detection of Fe3+ even after repeated rounds of quenching (reversibility) by acetate in real human blood samples and cells in vitro. Significantly trace levels of Fe3+ ions up to 8.2 nM could be detected, remaining unaffected by the existence of various other metal ions. The obtained results are validated by AAS and ICP-OES methods. A portable test strip is also fabricated for quick on field detection of Fe3+. As iron is a ubiquitous metal in cells and plays a prominent role in biological processes, the use of this probe to image Fe3+ in cells is a substantial development towards biosensing. Cytotoxicity studies also proved the nontoxic nature of this probe